cephadm: Move DB/WAL from HDD to SSD

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Hello,

I posted this on the Reddit sub, but it was suggested I might get better responses here.

I am running a 5-node Ceph cluster (v18.2.2) installed using "cephadm".

I am trying to migrate the DB/WAL on our slower HDDs to NVME; I am following this article:

https://docs.clyso.com/blog/ceph-volume-create-wal-db-on-separate-device-for-existing-osd/

I have a 1TB NVME in each node, and there are four HDDs. I have created the VG ("cephdbX", where "X" is the node number) and four equal-sized LVs ("cephdb1", "cephdb2", "cephdb3", "cephdb4").

On the node I am trying to move the DB/WAL first, I have stopped the systemd OSD service for the OSD I am doing this first to.

I have switched into the cephadm shell so I can run the ceph-volume commands, but when I run:

ceph-volume lvm new-db --osd-id 10 --osd-fsid 474264fe-b00e-11ee-b586-ac1f6b0ff21a --target cephdb03/cephdb1

I get the following error:

--> Target path cephdb03/cephdb1 is not a Logical Volume
Unable to attach new volume : cephdb03/cephdb1

If I run 'lvs' in the cephadm shell, I can see the LVs (sorry about the formatting; hopefully you can view it in a way that it isn't a big "jumble"):

LV                                             VG                                        Attr       LSize    Pool Origin Data%  Meta%  Move Log Cpy%Sync Convert
  osd-block-f85a57a8-e2f5-4bda-bc3b-e99d8b70768b ceph-341561e6-da91-4678-b6c8-0f0281443945 -wi-ao----   <1.75t
  osd-block-f1fd3d53-4ed9-4492-82a0-4686231d57e1 ceph-65ebde73-28ac-4dac-b0cb-4cf8df18bd4b -wi-ao----   16.37t
  osd-block-3571394c-3afa-4177-904a-17550f8e902c ceph-6c8de2ed-cae3-4dd9-9ea8-49c94b746878 -wi-a-----   16.37t
  osd-block-41d44327-3df7-4166-a675-d9630bde4867 ceph-703962c7-6f28-4d8b-b77f-a6eba39da6b2 -wi-ao----   <1.75t
  osd-block-438c7681-ee6b-4d29-91f5-d487377c3ac9 ceph-71cc35c4-436d-42b7-a704-b21c2d22b43b -wi-ao----   16.37t
  osd-block-2ebf78e8-1de1-464e-9125-14a8b7e6796f ceph-7c1fe149-8500-4a41-9052-64f27b2cb70b -wi-ao----   <1.75t
  osd-block-ca347144-eb84-4e9f-bfb5-81d60659f417 ceph-92595dfe-dc70-47c7-bcab-65b26d84448c -wi-ao----   16.37t
  osd-block-2d338a42-83ce-4281-9762-b268e74f83b3 ceph-e9b51fa2-2be1-40f3-b96d-fb0844740afa -wi-ao----   <1.75t
  cephdb1                                        cephdb03                                  -wi-a-----  232.00g
  cephdb2                                        cephdb03                                  -wi-a-----  232.00g
  cephdb3                                        cephdb03                                  -wi-a-----  232.00g
  cephdb4                                        cephdb03                                  -wi-a-----  232.00g
  lv_root                                        cephnode03-20240110                       -wi-ao---- <468.36g
  lv_swap                                        cephnode03-20240110                       -wi-ao----   <7.63g

All the official docs I read about it seem to assume the Ceph components are installed directly on the host, rather than in containers (which is what 'cephadm' does)

Any advice for migrating the DB/WAL to the SSDs when using 'cephadm'?

(I could probably destroy the OSD and manually re-create it with the options for pointing the DB/WAL to the SSD, but I would rather do it without forcing a data migration, otherwise I would have to wait for that with each OSD I am migrating)

Followup question: if I do seem to have to go the route of destroying the OSD and re-creating it with the flags for point the DB/WAL to the SSD partition, the syntax I have seen is this:

ceph-volume lvm prepare --bluestore --block.db --block.wal --data VOLUME_GROUP/LOGICAL_VOLUME

but the above command seems to only specify the location for the data? Should the syntax be more like:

ceph-volume lvm prepare --bluestore --block.db VG2/LV1 --block.wal VG2/LV1 --data /dev/sda

(assuming my HDD is /dev/sda)?

Thanks! :-)
_______________________________________________
ceph-users mailing list -- ceph-users@xxxxxxx
To unsubscribe send an email to ceph-users-leave@xxxxxxx



[Index of Archives]     [Information on CEPH]     [Linux Filesystem Development]     [Ceph Development]     [Ceph Large]     [Ceph Dev]     [Linux USB Development]     [Video for Linux]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]     [xfs]


  Powered by Linux